Antenna



' Jan. 22, 1935.

H\6H FREQUENCY APPARATUS H\GH FREQUENCY APPARATUS YS 0 wm HMM MGP HMM. F

Patented Jan. 22, 1935 In Germany 6 Claims.

This invention `relates to an antenna arrangement adapted to different It has been found in cases where frequently necessary to Wave is short that it is working waves.

the working feed the energy from the transmitter equipment to the aerial by way of what is known as an enand energy-feed line can of a tuned transformer.

be insured by the aid In special instances it is also feasible to insure such adaptation without a transformer. However,

whenever the necessity arises to alter the wave-length, the condition of adaptation is lost because of characteristic impedance this lmeans a change and a consequent alteration in coupling or repeating resistance.

According to this invention, a change in the wave-length is accompanied by a change in the constants'of the aerial, suchchange being insured by the alteration of the length of the antenna, so that for all waves the relationship between antenna length and wave-length and thus also the characteristic impedance yremain unvaried. Hence, it is secure adaptation feasible in this manner to between antenna and energyfeed line (up-lead) throughout the entire working wave range, it being, by whether the scheme is utilized the way, immaterial for sending or for receiving. Theparticular method of varying the length of the antenna forms no part, per se,

of the present invention,

but reference, however,

is made to an arrangement suitable for adjusting the antenna length which is disclosed in an application Serial No.' 674,024 f'11ed` 'by Werner Buschbeck June The present more detail by the aid of ments illustrated in Figures 1,

of illustration.

Referring to the aerial is equal to 1/4 there is a current node at the 2, 1933, by way of example only. invention shall be explained in three practical embodi- 2 and-3 which' represent antenna arrangements given by way- Figure 1, suppose the length of wave-length, so that top of the antenna, and an anti-node at the base end thereof. The characteristic impedance of a vertical antenna of M4 height amounts to, let us say,

35 ohms.

'Hence,` the surge Vimpedance of the up-lead to feed the said antenna in the current loop (anti-node) energy-feed line of this sortis by two concentric tubes,

should also be 35' ohms.

An easily obtained the inner one of which may be a wire of thickness as shown and which is connected with the aerial, while the outer one is grounded. The outer tube could also be dispensed with provided the inner tube or `wire is 'erlim .YGer.intuir.'Y Gesellschaft; Vfr" Dahtvltse .11., Berlin, Germany,

assigner., to y A [Tele-r correspondingly spaced apart from earth. At

' any rate in the case of such a M4 antenna recourse is had to a dissymmetric energy-feed line (Fig. l). Since the radiation resistance of the antenna is determined by the length of the antenna and the operating be kept constant, means are provided consisting of a drum C and a crank handle H to Vary the lengthy of the antenna as the wave length is changed. A weight W is attached to the inner conductor of the transmission line.

Now yreferring to Figure 2, suppose the aerial has a length equal to Vgl; then current nodes will be present at both ends, and an anti-node in the middle. The characteristic impedance of an aerial of 1/2 wave-length amounts to, let us say, '70 ohms. The surge impedance of the energy-feed line for feeding in the current loop therefore should likewise be 70 ohms. In addition it should be symmetric (Fig. 2). i Such an up-lead may be built up of two conductors spaced somewhat apart from each other, or else of two concentric cables whose outer envelopes are inter-connected, and which likewise may be grounded, such as shown in Fig. 3.

I claim:

1. In combination, an unloaded, quarter wave length, single wire, variable length, vertical antenna, high frequency apparatus, a horizontal transmission line of fixed length extending between said Ahigh frequency apparatus and said antennaand directly connected to said antenna, and means for varying the length of said vertical antenna for different wave lengths whereby the characteristic impedance of said transmission line always matches the radiation resistance of said antenna.

2. In combination, a linear, quarter -wave length antenna, high frequency apparatus, a transmission line of fixed length extending from said high frequency apparatus to said antenna and directly connected to said antenna, said transmission line having a characteristic impedance substantially equal to the radiation resistance of, said antenna, thed'antenna being adjustable to always equal a quarter wave length with change infrequency of said high frequency apparatus so that the radiation resistance is kept constant and matches the characteristic impedance of said transmission line.

3. A combination as defined in claim 2 characterized in this, that said transmission line vcomprises a concentric conductor cable having inner and outer tubes insulatingly separated throughout their lengths, said outer tube being connectwave length and must v lI0 antenna and maintaining constant the valuelof the radiation resistance of said antenna for yar;

rious lengths thereof. I Y

5. In combination, an' unloaded one--q'u`arter Wave length antenna,` high `frequency apparatus, a concentric conductor transmission line "conprising inner andvouter tubes insulatingly separated throughout their lengths extending y,between f apparatus and said antenna and directly connected to said antennafsaidouter,

said highfrequency tube being connected to ground and said inner tube being connected to said antenna, the characteristic impedance of said transmission line matching the radiation resistance of said antenna, and means for adjusting the length of said antenna for `different VWaye lengths.,

6.v In'an antenna system having high frequency apparatus, an unloaded "qua'rterwav'e length antenna of variable length, and a transmission line Aextending from said high frequency apparatus 10 uand directly connected to said antenna, the method of operation ywhich comprises matching the characteristic impedance of said transmission line to equal the radiation resistance of said quarter wave length rantenna and maintaining constant 15 the radiation resistance of said antenna for different quarter wave length values thereof.

ALBRECHT GOTHE. 

